A conventional multiphase circuit breaker generates ionized gases within each phase of the circuit breaker during the circuit interrupt condition. Modern circuit breaker designs are more compact and generate additional power in smaller spaces than conventional circuit breakers. Due to the reduction of internal space and the increased power generation, the gases produced are more intense and are at higher temperatures. When a compact current limiting circuit breaker, such as described in U.S. Pat. No. 4,963,849 entitled "Compact Current Limiting Circuit Breakers" is used within an industrial power distribution circuit, intense arc gases are generated during overcurrent circuit interruption. These high temperature gases must exit the circuit breaker enclosure in order to prevent the circuit breaker enclosure from becoming over-stressed. Ventilated circuit breakers provide openings within the circuit breaker enclosure to allow the ionized gas to exit the circuit breaker in a controlled manner.
The U.S. patent application No. 07/736,673, filed Jul. 26, 1991, entitled "Molded Case Circuit Breaker Arc Exhaust Gas Controller" describes one means for controlling the egress of gases from the circuit breaker enclosure. The arc gases exiting through the ventilation slot of one line terminal compartment must be prevented from contacting a line terminal connector within an adjacent line terminal compartment to prevent a so-called "phase-to-phase" fault. The typical approach to prevent the occurrence of short circuit between the line end conductors of different phases is to tape each conductor with insulating tape. This practice is labor intensive and expensive.
The U.S. patent application No. 07/836,573, filed Feb. 18, 1992, entitled "Arc-Proof Molded Case Circuit Breaker" describes one means of decreasing the intensity of the exiting arc exhaust gases so that the connecting busbars need not be separately shielded. Some means must be employed to prevent the ionized gases from contacting the associated grounded enclosure to thereby prevent the occurrence of a so-called "phase-to-ground" fault. Fasteners, such as screws, which secure the circuit breaker to the power take-off enclosure are in close proximity with the line end conductors. The high current passing through these conductors may arc across and cause a short circuit. The problem is often addressed by applying insulating epoxy to isolate the screws, a costly practice which requires additional space. Applying such epoxy, frequently called "potting," becomes problematic when the assembly must be disassembled and the operator must access the screws.
One purpose of this invention is to redirect gases exiting from the circuit breaker phases and to isolate conductors of adjacent phases from each other to avoid short circuits without requiring taping of the conducting connectors that are attached to the circuit breaker.
Another purpose of the invention is to isolate the circuit breaker mounting screws to prevent the occurrence of short circuits between the screws and the conductors within the power take-off assembly.